Mining machine cutting and breaking arm having sensing means



W. R. EBERLE Sept. 3, 1963 I MINING MACHINE CUTTING AND BREAKING ARM HAVING SENSING MEANS Filed July 19, 1960 5 Sheets-Sheet l N RN m INVENTOR; WILLIAM R. EBERLE, BY L3 ATT'Y I .V../ b w MINING MACHINE CUTTING AND BREAKING ARM HAVING SENSING MEANS Filed July 19, 1960 w. R. EB'ERLE Sept. 3, 1963 5 Sheets-Sheet 2 INVENTOR; WILLJAM R EBEIRLE,' BY q HTT 'Y Sept. 3, 1963 w. R. EBERLE 3,102,713

MINING MACHINE CUTTING AND BREAKING ARM HAVING SENSING MEANS Filed July 19, 1960 5 Sheets-Sheet 3 Big. 4

55 45 4g 44 22 22 45 W Fly. 3

INVENTOR, WILLIAM R. EBERLE,

fITT' 5 Sheets-Sheet 4 w. R. EBERLE INVENTOR; WILLIAM REBERLE,

M I; TTY

Sept. 3, 1963 MINING MACHINE CUTTING AND BREAKING ARM HAVING SENSING MEANS Filed July 19, 1960 MINING MACHINE CUTTING AND BREAKING ARM HAVING SENSING MEANS Filed July 19, 1960 W. R. EBERLE Sept. 3, 1963 5 Sheets-Sheet 5 .N MB 3%. R M ym 0' L 4 W Unite States Patent MINING MACHINE CUTTING AND BREAKING ARM HAVING SENSING MEANS William R. Eberle, Columbus, Ohio, assignor, by mesne assignments, to Jeffrey Gallon Manufacturing Company, a corporation of Ohio Filed July 19, 1960, Ser. No. 43,871

12 Claims. (Cl. 262-26) The instant invention relates to mining machines, and more particularly to sensing devices for use in mining ma- I chines for sensing the advance of the cutting and breaking means of such machines into materials of different hardness from the selected material of the mine face which it is desired to remove by operation of the mining machine.

It is an object of the instant invention to provide a cutting and breaking arm for a mining machine including improved sensing means for sensing materials of diiferent hardness in the mine face.

It: is another object of the instant invention toprovide a mining machine cutting and breaking arm including a bit assembly which is movable relatively to the main body of the cutting and breaking arm in response to the advance of the cutting and breaking arm and the bit assembly into materials of different hardness.

' It is a further object of the instant invention to provide a mining machine cutting and breaking arm including a bit assembly which is movable relatively to the main body of the arm, and having an element in the main body which is movable by the bit assembly to produce a signal indicating advance of the cutting and breaking arm and the bit assembly into materials of different hardness.

is also an object of the instant invention to provide a mining machine cutting and breaking arm including an element in the main body of the arm which is movable irfresponse to the advance of the cutting and breaking arm into materials of different hardness, and having resilient means bearing on the element to apply'force thereto, said resilient means being adjustable for adjustment of the force imposed on the element to thereby adjust the force required to move the element relatively to the main body of the cutting and breaking arm.

-It is still another object of the instant invention to provide a mining machine cutting and breaking arm including an element mounted in the arm for movement relatively thereto in response to the advance of said arm into material of different hardness from selected material adapted to be removed by the cutting and breaking arm, and including a switch operated by movement of the element to produce a signal indicating the advance of the cutting and breaking arm into material other than the selected material.

Still a further object of the instant invention is to provide a mining machine cutting and breaking arm including an element movably mounted in the arm for movement relatively thereto in response to the advance of the cutting and breaking arm into material of different hardness from selected material which is adapted to be removed by the cutting and breaking arm, and including a switch operated by movement of the element to produce a signal indicating the advance of the cutting and breaking arm into material of different hardness from the selected material, said switch being adjustable relatively to the element to adjust the movement of the element required for operation of the switch.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings:

FIG. 1 is a side elevational view, partially in section,

P we

of a portion of a mining machine including the cutting and breaking arm of the instant invention;

FIG. 2 is a side elevational View, partially in section, of the cutting and breaking arm of this invention;

FIG. 3 is a front elevational view, partially in section, of the cutting and breaking arm;

FIG. 4 is a sectional view of a portion of the cutting and breaking arm, taken on the line 44 in FIG. 3;

FIG. 5 is a side elevational view, in section, of elements of the electrical system in the rear of the mining head;

FIG. 6 is an elevational view of certain elements of the electrical system, taken on the line 66 in FIG. 5;

FIG. 7 is a side elevational view of a modified cutting and breaking arm constructed in accordance with the instant inevntion;

FIG. 8 is a front elevation view, partially in section, of the modified cutting and breaking arm;

FIG. 9 is a sectional view of the modifited cutting and breaking arm, taken on the line 99 in FIG. 7; and

FIG. 10 is a sectional view of a portion of the modified cutting and breaking arm, taken on the line 1010 in FIG. 8.

The instant invention is in a cutting and breaking arm for a continuous miningmachine, and more particularly in a sesning device for such a cutting and breaking arm for sensing the advance of the cutting and breaking arm into material in the mine face other than the selected material thereof which the mining machine is adapted to remove from the mine face. The mining machine to which the instant invention is applicable is intended primarily for use in the mining of coal. The coal is normally found in underground seams, above and below which there is usually rock which is the greater hardness than the coal itself. The sensing device which is disclosed herein includes a movable bit assembly in the cutting and breaking arm, which yields and moves relatively to the main body of the cutting and breaking arm when it is advanced into material which is of a different hardness from the selected material of the mine face, which is the coal. Since the rock which is found above and below the coal seams is relatively harder than the coal, the bits of the cutting and breaking arm will encounter a greater resistance to the operation thereof in the rock than is the case when they are operated in the relatively softer coal. This condition of operation is utilized to sense the materials of the mine face by the provision of a relatively movable bit assembly, which is moved when it encounters the greater resistance of the harder material in the mine face, which is the rock.

The complete system for utilization of the mining machine cutting and breaking arm including the sensing device thereof is disclosed and described in the copending patent application of Sterling C. Moon, Serial No. 838,- 110, filed September 4, 1959, for Continuous Mining Machine and Control System Therefor, assigned to the assignee of this application. Reference may be had to this patent application for the description of a continuous mining machine which is adapted to incorporate and utilize the cutting and breaking arm described herein and the sensing device thereof.

Referring to the drawings, the continuous mining machine includes a lower mining head 11, which extends across the front of the mining machine, and includes a gear housing 12 within which there is provided a plurality of gears 13, one of which is shown in FIG. 1. The several gears 13 are arranged in a train extending across the lower mining head 11, to synchronously drive a plurality of shafts 14, each of which is secured to 'a gear 13 by a key .15. Each shaft 14 extends forwardly from the lower mining head 1-1 at spaced positions across the my y front of the lower mining head ll. The rear end of a shaft 14 is rotatably supported within the lower mining head 11 by a suitable tapered roller bearing 16, and another tapered roller bearing 17 rotatably supports the shaft 14 at the front of the head ii.

A radially extending cutting and breaking arm 20 is secured to the forward end of the shaft 14 to be rotated thereby. In the operation of the mining machine, the cutting and breaking arms 20 on the several shafts 14 are advanced into the mine face by the forward propulsion of the mining machine, and by the simultaneous rotation of the cutting and breaking arms 20 by their respective shafts 14 the cutting and breaking arms 20 operate to remove selected material from the mine face by the cutting and breaking action thereof.

The cutting and breaking arm 20 at each side of the lower mining head 11 includes the sensing device of the instant invention, since it is only necessary to sense the material in the mine face at corner perimetral portions of the area of the mine face from which material is removed by the mining machine, in the manner explained in detail in the aforementioned copending patent application of Sterling C. Moon, Serial No. 838,110.

The cutting and breaking arm 20 includes a main body 21 which is formed at its outer end with several bit holders 22 for the reception of bits 23. Radially inwardly from the bit holders 22, the main body 21 includes several more bit holders 24, which are adapted to receive bits 25. The several bits 23, 25 are rigidly supported on the main body 21, and are adapted to be worked into the selected material of the mine face by operation of the cutting and breaking arm 20. The bits 23, 25 cut into the material of the mine face and cause it to be broken out of the mine face to thereby remove the material therefrom. The mining machine which incorporates the cutting and breaking arms 20, also includes suitable collecting and conveying means for taking the mined material away from the area of the mine face, to thereby permit the continued advance of the mining machine and the cutting and breaking arms 29 into the mine face.

The cutting and breaking arm 2i) further includes a sensing bit assembly 26, which is supported or mounted on the main body 21 for movement relatively thereto,

as best seen in FIGS. 3 and 4. The main body 21 isformed with a relieved end portion 27, in which there is a bore 28 formed on an axis which is parallel to the axis of the shaft 14. A flanged bushing 22 is inserted into the bore 28 from one side of the relieved end portion 27, and a similar flanged bushing 30 is inserted into the bore 28 from the other side of the relieved end portion 27. As seen in FIG. 4, the bushings 29, 30 are of such length that they are spaced from each other when fully inserted into the bore 28, to provide an annular passage 31 between the ends of the bushings 29, 30 for lubrication of the assembly. The sensing bit assembly 26 is formed with a bifurcated end 32, which is adapted to be placed over the relieved end portion 27, hearing against the flanged bushings 29, 30. The bifurcated end portion 32 of the sensing bit assembly 26 includes a bore 33, which is aligned with the bores of the bushings 29, 30, for the reception of a pin 34 extending through the bifurcated end portion 32 and through the bushings 29, 30. At the rear side of the sensing bit assembly 26 there is provided a washer 35, which is received in a circular recess 36 and bears against the bifurcated end 32 of the bit assembly 26. A pair of cap screws 37 are inserted through bores in the washer and threaded into the pin '34 for securing the sensing bit assembly 26 on the relieved end portion 27 of the main body 21. The pin 34 includes an internal duct 38, in the outer end of which there is placed a grease fitting 39 for lubrication of the assembly, the lubricant being delivered to the annular passage 31 formed between the inner ends of the bushings 29, 30. The bit assembly 26 is thus rotatably mounted on the relieved end portion 27 of the cutting and breaking arm main body 21, on an axis that is parallel to the axis of rotation of the cutting and breaking arm 20. The main body 21 includes an integral stop 40 which abuts the bit assembly 26 and limits the rotation thereof in a counter-clockwise direction. The sensing bit assembly 26 includes an integral bit holder 41 for the reception of a bit 42, which is adapted to operate in the same manner as the bits 23, 25 to cut into the selected material of the mine face.

The sensing bit assembly 26 includes a wall 43 that is spaced from an adjacent wall 44 of the cutting and break ing arm main body 21. A pin 45 is slidably mounted in a bore 46 in the main body 21 and extends between the latter and the sensing bit assembly 26, abutting the wall 43 and spanning the distance between the adjacent walls 43, 44. The pin 45 has a close fit in the bore 46 to close the latter, but is freely slidable therein. A dust and water seal 48 is disposed behind the bore 46 engaging the pin 45 to prevent entrance of dust and water through the bore 46 and around the pin 45. Behind the bore 46 there is formed a threaded wall chamber 49 in which there is received a spring housing 50, the outer surface of which is formed with threads to permit the spring housing 54} to be threaded into the threaded wall chamber 49. The pin 45 is formed with an annular flange 51 intermediate the opposite ends thereof, and near the outer end of the spring housing 50, there is formed an internal flange 52 which overlies the annular flange 51 and is spaced from the later. A plurality of coned disc springs 55, arranged in stacked pairs, are placed on the pin 45 between the annular flange 51 thereof and the internal flange 52 of the spring housing 50.

The rotational movement of the sensing bit assembly 26, relatively to the cutting and breaking arm main body 21 in a counter-clockwise direction, as seen in FIG. 3, is limited by the stop 40, and accordingly, the reciprocation of the pin 45 in a direction towards the bit assembly 26 is similarly limited. Rotational movement of the sensing bit assembly 26 in a clockwise direction relatively to the cutting and breaking arm main body 21, will produce sliding movement of the pin 45 in the bore 46 relatively to the cutting and breaking arm main body 21. The spring housing 50 is fixed in the main body 21 by its threaded engagement with the threaded wall chamber 49, and accordingly, the springs 55 act between the flange 52 of the spring housing 50 and the flange 51 of the pin 45, to apply a force to the latter to urge it in a direction towards the bit assembly 26 and thereby urge the latter against the stop 44), which sets the limit position of the bit assembly 26 in a counterclockwise direction. Rotative movement of the bit assembly 26 in a clockwise direction is in opposition to the force of the springs 55 on the pin 45. The force exerted by the springs 55 on the pin 45 may be increased or decreased by adjustment of the spring housing 50 inwardly or outwardly, respectively, in the chamber 49. Thus, by turning the spring housing 5i further into the chamber 49, the springs 55 are flattened, thereby increasing the force thereof acting on the pin 45 and opposing clockwise rotative movement of the sensing bit assembly 26, whereby it will require a greater force acting on the bit assembly 26 to produce rotative movement thereof. The opposite result is achieved by turning the spring housing 50 outwardly with respect to the chamber 4?, which causes the coned disc springs 55 to expand in the spring housing 50.

The adjustable spring housing 50 constitutes a calibration device, whereby the force of the coned disc springs 55 acting on the pin 45 may be adjusted so that there will be no rotative movement of the sensing bit assembly 26 when it is operating in selected material, such as coal. In this circumstance the force brought to bear on the bit assembly 26 by the operation of its bit 42 in the coal will be insufficient to overcome the force of the springs 55 acting on the pin 45, and there Will be no sliding movement of the pin 45 in the bore 46. However, when the bit 42 is operated in material such as rock, which is relatively harder than the coal, there will be an increased force acting on the bit assembly 26, which is commensurate with the greater resistance of the rock to the cutting action of the bit 42. This greater force acting on the sensing bit assembly 26 will overcome the force of the coned disc springs 55 and produce sliding movement of the pin 45 in the bore 46. By this operation of the sensing bit assembly 26 there is produced a sensing function indicating the advance of the cutting and breaking arm into material of diiierent hardness from the selected material. The sensing action of the bit assembly 26 manifests itself as a sliding movement of the pin 45, produced by the rotative movement of the bit assembly 26-.

The internal flange 52 of the spring housing 50 is formed with a bore 56 through which the pin 45 extends to a position beyond the spring housing 50. A switch plate 57 is secured to the outer end of the pin 45 by a nut 58. The switch plate 57 is disposed in a chamber 59 formed in the cutting and breaking arm main body 21. At the left side of the cutting and breaking arm main body 21, as viewed in FIG. 3, there is provided a relatively large threaded opening 60 through which access may be had to the chamber 59 by reaching through the opening 60. The switch plate 57 may be removed from the end of the pin 45, and the spring housing 50 is thus made accessible for adjustment thereof to calibrate the coned disc springs 55 for operation of pin 45 and the sensing bit assembly 26 to serve the sensing function as above described. The threaded opening 60 is normally closed and sealed by a cover 61 threaded into the opening 60. 7

Within the chamber 59 there is provided a switch mounting plate 64 which is pivotally secured to the cutting and breaking arm main body 21 by a shouldered screw 65, which permits the switch mounting plate 64 to pivot about the axis of the screw 65. An electrical switch 66 is secured to the lower end of the switch mounting plate 64. The switch 66 may be a microswitch, which includes a switch actuating lever 67 in the form of a spring lever that is disposed to lie behind the switch plate 57 abutting the latter. Sliding movement of the pin 45 will cause the switch plate 57 to operate the actuating lever 67 to operate the switch 66. In the present embodiment of the invention, the switch is normally open, and it is closed upon operation of the actuating lever 67 as aforementioned.

At the upper end of the switch mounting plate 64 there is provided a link 68 which is pivotally connected to the end of the switch mounting plate 64 by a pin 69. An adjusting screw 70' is formed with threads at its inner end, and is threaded into the body of the link 68. The adjusting screw 70 includes an annular integral shoulder 71 which bears against a lug 72 formed in the chamber 59, as an integral part of the main body 21. An unthreaded portion of the adjusting screw 70' extends through a bore 73 in the lug 72. The outer end of the adjusting screw 70 beyond the lug 72 is threaded for the reception of a nut 74 by which the adjusting screw 70 may be fixedly secured to the lug 72, with the shoulder 71 bearing against the lug 72.

The position of the switch mounting plate 64 and the switch 66 may be adjusted relatively to the switch plate 57. In order to do this, the nut 74 is turned off the outer end of the adjusting screw 70 and the latter 'is then turned into or out of the link 68, thereby pivoting the switch mounting plate 64 on the screw 65 and ad justing the position of the switch mounting plate 64 and the switch 66 carried thereby. After adjustment has been made, the nut 74 may be turned onto the outer end of the adjusting screw 70, thereby locking the adjusting screw 70 to the lug 72. A clip 75 is secured to the lug 72 by a screw 76. A spring 77 is hooked to the clip 75 and to the switch mounting plate 64, applying a force to the latter urging it in a counter-clockwise direction, as viewed in FIG. 3, and serving to compensate for any loose fit of the parts and maintaining the switch mounting plate 64 and the switch 66 in fixed position relatively to the switch plate 57.

At the left side of the cutting and breaking arm main body 21, as viewed in FIG. 3, there is provided a threaded opening 80, which is disposed adjacent the outer end of the adjusting screw 70. The threaded opening 80 is sufficiently large to permit the insertion of a wrench to loosen or tighten the nut 74, and also for the insertion of a screwdriver for turning the adjusting screw 70. The threaded opening 80 is normally closed by a threaded plug 81 turned into the opening 80. At the rear of the cutting and breaking arm main body 21111613 is provided a large threaded opening 82, which is disposed adjacent the switch mounting plate 64 and the switch 66, and provides access to these parts for replacement or repair as may be necessary. The threaded opening 82 is closed by a cover 83 that is threaded into the opening 82 and locked therein.

Above the chamber 59 there is provided a bore 85 which leads into the chamber 59 and in which there is disposed a two conductor cable 86 that is connected to the switch 66. The two conductor cable 86 is secured in the bore 85 by a packing nut 87, which is threaded into the end of the bore 85 and holds packing and insulating washers 83 in place in the bore 85. At the front of the cutting and breaking arm main body 21 there is provided a threaded opening 89 through which access is provided to the upper end of the bore 85 and to the two conductor cable 86. The threaded opening 89 is normally closed by a plug 90 threadedly secured therein.

The two conductor cable 86 is led upwardly in the cutting and breaking arm main body 21 through a com tinuing bore 91 into the shaft 14. An insulating bushing 92 surrounds the two conductor cable 86 where it enters the shaft 14. An axially disposed bore 93 is provided in the shaft 14 for leading the two conductor cable 86 to the rear end of the shaft 14, and a packing nut 94 and packing and insulating washers 95 are provided for securing the two conductor cable 86 in place in the end of the shaft 14.

At the end of the shaft 14 there is provided a mounting block 96, which is formed of insulating material. The two conductors 97, 98 of the two conductor cable 86 are led through an aperture 99 in the mounting block 96. One conductor 97 is electrically connected toa contact spring 100, which is secured to the rear of the mounting block 96 and has its contact portion axially disposed with respect to the shaft 14, as seen in FIGS. 5 and 6. The other conductor 98 of the two conductor cable 86 is electrically connected to a terminal post 101 on the rear face of the mounting block 96. A brush mounting block 102 is secured to the rear end of the shafit 14 by a pair of cap screws 103, and a brush holder 104 is secured to the brush mounting block 102 by a pair of machine screws 105. The brush holder 104 includes a brush 106 backed by a spring 107, disposed parallel to the axis of the shaft 14. A conductor 103 is connected to the terminal 101, and is led through the mounting block 96 to the brush holder 164 and is connected to the brush 106.

At the rear of the lower mining head 11 there is provided a cover and commutator assembly 110, which is secured to the lower mining head 11 by a plurality of cap screws 111. The cover and commutator assembly 110 comprises a mounting cover 112 to the inner face of which there is secured a keeper plate 113. The cover 112 is formed with an axially extending post 114 projecting inwardly from the inner face thereof, and on which there is mounted a face commutator 115. An insulating bushing 116 is provided on the post 114, between the post 114 and the commutator 115, to insulate the latter from the post 114. A plurality of insulating shims 117 are disposed between the commutator and the cover 112 to insulate the commutator 115 trom the cover 112, and

i also to permit adjustment of the position of the commutator 115 in an axial direction. An insulating block 118 is secured to the front end of the post 114 with a plurality of insulating shims 119 being interposed between the commutator 115 and the insulating block 118 to permit adjustment of the position of the insulating block 118. A machine screw 120 is threaded through the insulating block 118 and into the post 114 .for securing the insulat ing block 118 to the post 114. A contact plate 121 is secured to the front of the insulating block 118 by several machine screws 122, and is formed with an axially extending contact 123 engaged by the contact spring 100. The contact 123 being included as an element of the cover and commutator assembly 110 is maintained in fixed position, and the contact spring 160 being included on the shaft 14 rotates with the latter, but maintains electrical contact with the contact 123 in all positions of rotation. The brush 106 is disposed in alignment with the segments of the face commutator 115, and as the brush 106 revolves with the shaft 114, it will successively contact the segments of the commutator 115. Thus by means of the commutator 115 and the contact 123, electrical connections are provided for completing a circuit which includes the conductors 97, 98 and the switch 66.

The rear of the cover 112 is formed with a bore 124 for a conductor cable 125 that is led into the cover and commutator assembly 110. The cable 125 is secured in the bore 124 by a packing nut 126 and packing and insulating washers 127. The conductor cable 125 includes a plurality of conductors, one of which is connected to a terminal 128 that is secured to the contact plate 121 by a machine screw 122. The other conductors of the conductor cable 125 are individually secured to several segments of the commutator 115 disposed in a quadrant which corresponds to a quadrant of operation of the cutting and breaking arm 20, as is fully explained in the copending patent application of Sterling C. Moon, Serial No. 838,110. The electric circuit elements described herein provide for energizing a circuit, including signalling elements, Which will provide signals related to rota tional positions of the cutting and breaking arm 20, and indicating advance of the cutting and breaking arm 20 into material which is of different hardness from the selected material in which it is desired to operate the cutting and breaking arm 20.

The mining machine to which the instant embodiment of the invention disclosed herein is applicable includes upper and lower mining heads as described in the copending patent application of Sterling C. Moon, Serial No. 838,110. The description hereinabove has been with respect to the lower mining head 11 and the cutting and breaking arms 20 thereof. The upper mining head is constructed similarly to the lower mining head 11, and includes a plurality of cutting and breaking arms 130, illustrated in FIGS. 7 to 10, which are of substantially shorter radial length than the lower cutting and breaking arms 20. The two upper cutting and breaking arms 130 which are disposed at the sides of the mining machine are each provided with a sensing device similar to the sensing device included in the lower cutting and breaking arm 20, adapted to sense the material of the mine face for providing a signal indicating the advance of the cutting and breaking arms 130 into material of diiferent hardness from the selected material. It will be understood that the entire sensing system includes four cutting and breaking arms provided with sensing devices, which are disposed at the corners of the area of the mine face in which the cutting and breaking arms operate, and each arm provides a sensing function in a corner quadrant located in a perimetral portion of the mine face area from which material is removed by the cutting and breaking arms.

Referring to FIGS. 7 to 10, the upper cutting and breaking arm 130 includes a main body 131 with a relieved end portion 132 having a bore 133 formed on an axis that is parallel to the axis of the shaft 134 to the end of which the cutting and breaking arm is secured for rotation of the latter by the shaft 134. It will be understood that the upper mining head includes a gear system similar to that included in the lower mining head 11 by which the shaft 134- is rotated. A pair of flanged bushings 135, 136 are placed in the opposite ends of the bore 133, with the inner ends of the bushings 135, 136 being spaced from each other to form an annular passage 138 for the admission of lubricant. The cutting and breaking arm main body 131 is formed with a lubricating duct 137 communicating with the annular passage 138 to deliver lubricant to the latter. A grease fitting 139 is secured in the end of the lubricating duct 137 and is accessible from the front of the cutting and breaking arm main body 131. The grease fitting 139 is disposed in a threaded bore 140 which is normally closed by a plug 141 threadedly secured therein to prevent the accumulation of dust on the grease fitting 139.

The cutting and breaking arm 139 includes a sensing bit assembly 145, which is formed with a bifurcated end portion 146 that is fitted over the relieved portion 132, with the flanged bushings 135, 136 being disposed between the sensing bit assembly 145 and the relieved end portion 132 of the cutting and breaking arm main body 131. The bifurcated end portion 136 of the sensing bit assembly is formed with a bore 147, that is aligned with the bores of the bushings 135, 136 for the insertion therein of a pin 148, and the assembly is secured by a washer 149 overlying the bifurcated end portion 146 of the sensing bit assembly 145 and secured to the pin 148 by a machine screw 150. The sensing bit assembly 145 is thus mounted on the cutting and breaking arm main body 131 for rotative movement relatively thereto on the axis of the pin 148, as seen in FIG. 8. The main body 131 is formed with a stop 151 abutting one side of the sensing bit assembly 145 and limiting the rotative movement of the latter in a counterclockwise direction.

The sensing bit assembly 145 is formed with an in tegral bit holder 152, which is adapted to receive a bit 153. During operation of the cutting and breaking arm 130 the bit 153, and bits 154, the latter 'being secured in hit holders 155 integrally formed with the main body 131, are advanced into the material of the main face. When operating in the selected material of the mine face, which is the coal, the bit 153 of the sensing bit assembly 145 will simply operate to cut into the material, and there will be no rotative movement of the sensing bit assembly 145 in a clockwise direction. However, when the sensing bit assembly 145 and its bit 153 are advanced into material such as rock, which is substantially harder than the coal, the increased resistance of the harder material to the cutting action of the sensing bit 153 will produce rotative movement of the sensing bit assembly 145 in a clockwise direction, in the same manner as above described in connection with the lower cutting and breaking arm 20. The sensing bit assembly 145 is formed with a rear wall 156 that is spaced from an adjacent wall 157 of the main body 131, which spacing permits the clockwise rotative movement of the sensing bit assembly 145 relatively to the cutting and breaking arm main body 131.

The cutting and breaking arm main body 131 includes a pin 158 slidably supported in a bore 159 and extending towards the sensing bit assembly 145 and abutting the wall 156 thereof. Behind the bore 159' there is provided a dust and water seal 160 for sealing the area around the pin 158, and preventing the entrance of dust and water into the main body 131. A threaded wall chamber 161 is formed in the main body 131 behind the bore 159, and a spring housing 162 formed With a threaded outer wall is turned into the threaded wall chamber 161 surrounding the pin 158. The spring housing 162 has an internal flange 163 which overlies an annular flange 164 integrally formed on the pin' 158 approximately midway between its ends. A stack of coned disc springs 165, arranged in pairs, are disposed between the flanges 163, 164, with the force of the springs 165 being thereby applied to the pin 158 urge it against the wall 156 of the sensing bit assembly 145, to maintain the latter in its limit position in a counterclockwise direction abutting the stop 151. By adjustment of the spring housing 163 in the thrmded wall chamber 161 the [force applied to the pin 158 by the coned disc springs 165 may be increased or decreased, for adjustment of the :force acting on the sensing bit assembly 145 which is required to produce movement of the latter. This structure provides a means of calibrating the sensing device for the materials in which the cutting and breaking arm 130 is operated. Thus, by way of example, when operating in relatively soft coal, the force of the coned disc springs 165 on the pin 158 may be decreased, since the force acting on the sensing bit assembly 145 during the mining operation will be less in such coal.

The outer end of the pin 158 is provided with a switch actuator 166, which is disposed in engagement with an actuating lever 167 of an electrical switch 168, which may be a micro-switch. The switch 168 is mounted on a switch mounting plate 169 that is pivotally secured to the main body 131 by a pin 170 within a chamber 171 formed in the main body 131. The lower end of the switch mounting plate 169, as seen in FIG. 8, has a slot 172 through which there is passed a cap screw 173 that is threaded into the main body 131. By means of the cap screw 173 and the slot 172, the position of the switch 168, relatively to the switch actuator 166 of the pin 158, may be adjusted. By adjustment of the switch 168 as aforementioned, there is provided an adjustment of the movement of the pin 158 required for closing the switch 168, which will make the sensing device more or less sensitive in operation. Stated another way, by adjustment of the position of the switch 168, it may be closed by greater or lesser movement of the sensing bit assembly 145. Access is provided to the chamber 171 and the various elements of the sensing device therein through a relatively large threaded opening 174 formed at the left side of the cutting and breaking arm 130, as viewed in FIG. 8. The threaded opening -174 is normally closed by a cover 175 which is threadedly se cured in the opening 174.

The cutting and breaking arm main body 131 includes a bore 176 through which there is led a two conductor cable 177, the latter being secured in the bore 176 by a packing nut 178 and insulating washers 179. The two conductor cable 177 extends into the chamber 171 in the main body 131, and the individual conductors thereof are connected to the switch 168. The shaft 134 includes an axially disposed bore 180 through which the two conductor cable 177 is led to the rear of the upper mining head. At the rear of the upper mining head the two conductor cable is connected to electrical circuit elements constructed in the same manner as disclosed in connection with the lower mining head and illustrated in FIGS. and 6. There is thus provided another electrical circuit, in which the switch 168 is included for providing signals indicating the advance of the sensing bit assembly 145 and the cutting and breaking arm 130 into material of different hardness from the selected material in which it is desired to operate the cutting and breaking arm 130 and the sensing bit assembly 145.

By this invention there is provided a sensing device for use in connection with a rotatable cutting and breaking arm of a mining machine to indicate the advance of the cutting and breaking arm into materials of diiferent hardness from the selected material in which it is desired to operate the cutting and breaking arms. The sensing device includes a sensing bit assembly formed as an element of the cutting and breaking arm, and movable relatively to the main body of the cutting and breaking arm when the latter is advanced into material of different hardness from the selected material. Movement of the sensing bit assembly produces a signal in an electrical signaling sys tem by which the operator of the mining machine is informed of the advance of the cutting and breaking arm into material other than the selected mate-rial of the mine face, and he may then make appropriate adjustments of the mining machine to maintain the advance of the mining machine into the selected material of the mine face.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and applicant therefore wishes not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

l. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, a bore in said main body extending towards the sensing bit assembly, a pin slidably supported in said bore for movement relatively to the main body, said pin extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for transmission of relative movement of the sensing bit assembly to said pin for corresponding movement of said pin relatively to the main body, resilient means in said main body engaging the pin to urge it into abutting contact with the sensing bit assembly to yieldably oppose movement of the sensing bit assembly, means to adjust the force of the resilient means urging the pin into abutting contact with the sensing bit assembly to thereby adjust the force required to move the sensing bit assembly relatively to the main body, a switch in said main body, said pin including means for actuating said switch upon movement of said pin for translating relative movement of said pin to a signal for indicating the advance of said sensing bit assembly into material of ditferent hardness from said selected material, and means adjustably mounting the switch in the main body for adjustment of the switch relatively to the pin to adjust the movement of said pin required for actuation of the switch.

2. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, a bore in said main body directed towards the sensing bit assembly, a pin slidably supported in said bore for movement relatively to the main body, said pin extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for opposing movement of said sensing bit assembly and for transmission of relative movement of the sensing bit assembly to said pin for corresponding movement of said pin relatively to the main body, a switch in said main body, said pin including means for actuating the switch upon relative movement of said pin for translating relative movement of said pin to a signal for indicating the advance of said sensing bit assembly into material of different hardness from said selected material, and means for adjusting the position of said switch relatively to the pin to adjust the movement of said pin required for actuation of the switch.

3. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, an element supported in said main body for movement relatively to the main body, said element extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for opposing movement of said sensing bit assembly and 'for transmission of relative movement of the sensing bit assembly to said element for corresponding movement of said element relatively to the main body, a switch in said main body, said element including means for actuating said switch for translating relative movement of said element to a signal 'for indicating the advance of said sensing bit assembly into material of diflerent hardness from said selected material, a mounting plate pivotally mounted in said main body, means mounting the switch on said mounting plate, and means to adjust the position of the mounting plate and switch to change the position of the switch relatively to said element to thereby adjust the movement of said element required 'for actuation of said switch.

4. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said difierent handness material of the mine face, an element supported in said main body for movement relatively to the main body, said element extending beyond the main body and between the main body and the sensing bit assembly and abutting the bit assembly for opposing movement of said sensing bit assembly and for transmission of relative movement of the bit assembly to said element for corresponding movement of said element relatively to the main body, a switch in said main body, said element including means for actuating the switch for translating relative movement of said element to a signal for indicating the advance of said sensing bit assembly into material of diiferent hardness from said selected material, and means for adjusting the position of the switch in said main body to adjust the movement of said element required for actuation of said switch.

5. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit exteriorly mounted on the main body for movement relatively to the main body when the sensing bit is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, an element supported in said main body for movement relatively to the main body, said element extending beyond the main body to cooperate with the sensing bit to oppose movement thereof and for transmitting relative movement of the sensing bit to said element for corresponding movement of said element relatively to the main body, a switch in said main body, and said element including means for operating the switch upon movement of said element for translating relative movement of said element to a signal for indicating the advance of said sensing bit into material of different hardness from said selected material.

6. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, a bore in said main body extending towards the sensing bit assembly, a pin slidably supported in said bore for movement relatively to the main body, said pin extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for transmission of relative movement of the sensing bit assembly to said pin for corresponding movement of said pin relatively to the main body, a plurality of coned disc springs engaging the pin to urge it into abutting contact with the bit assembly to yieldably oppose movement of the bit assembly, a spring housing threaded into the main body and bearing against the springs :for application of the force of the springs between the spring housing and the pin and the force of the springs acting 'on the pin being adjustable by adjustment of the spring housing to thereby adjust the force required for moving the sensing bit assembly relatively to the main body, and means for translating relative movement of said pin to a signal for indicating the advance of said sensing bit assembly into material of different hardness from said selected material.

7. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different bardness material of the mine face, a bore in said main body extending towards the sensing bit assembly, a pin slidably supported in said bore for movement relatively to the main body, said pin extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for transmission of relative movement of the sensing bit assembly to said pin for corresponding movement of said pin relatively to the main body, resilient means comprising a coned disc spring on said pin and abutting the pin to urge it into abutting contact with the sensing bit assembly to yieldably oppose movement of the bit assembly, means for adjusting the (force of said spring on the pin urging the pin into abutting contact with the sensing bit assembly to thereby adjust the force required for moving the sensing bit assembly relatively to the main body, and means for translating relative movement of ,saidpin to a signal for indicating advance of said sensing bit assembly into material of different hardness from said selected material.

8. A mining machine cutting and breaking/arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exterionly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, a bore in said main body extending towards the sensing bit assembly, a pin slidably supported in said bore for movement relartively to the main body, said pin extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly -for transmission of relative movement of the sensing bit assembly to said pin for corresponding movement of said pin relatively to the main body, resilient means in said main body engaging the pin to urge it into ,abutting contact with the sensing bit assembly to yieldably oppose movement of the bit assembly, means to adjust the force of the resilient means urging the pin into abutting contact with the sensing bit assembly to thereby adjust the force required for moving the sensing bit assembly relatively to the main body, and means for translating relative movement of said pin to a signal for indicating the advance of said sensing bit assembly into material of different hardness from said selected material.

9. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, a bore in said main body directed towards the sensing bit assembly, a pin slidably supported in said bore for movement relatively to the main body, said pin extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for opposing movement of said sensing bit assembly and for transmisison of relative movement of the sensing bit assembly to said pin for corresponding movement of said pin relatively to the main body, and means for translating relative movement of said pin to a signal for indicating the advance of said sensing bit assembly into material of different hardness from said selected material.

10. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit assembly pivotally mounted on the main body exteriorly thereof for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, an element slidably supported in said main body for movement relatively to the main body, said element extending beyond the main body and between the main body and said sensing bit assembly and abutting the sensing bit usembly for opposing movement of said sensing bit assembly and for transmission of relative movement of the sensing bit assembly to said element for corresponding movement of said element relatively to the main body, and means for translating relative movement of said element to a signal for indicating the advance of. said sensing bit assembly into material of different hardness from said selected material.

11. A mining machine cutting and breaking arm for removing selected material from a mine :face, said cutting and breaking arm comprising a main body, a sensing bit assembly exteriorly mounted on the main body for movement relatively to the main body when the sensing bit assembly is advanced into material of different hardness from said selected material to sense said different hardness material of the mine face, an element supported in said main body (for movement relatively to the main body, said element extending beyond the main body and between the main body and the sensing bit assembly and abutting the sensing bit assembly for opposing movement of said sensing bit assembly and for transmission of relative movement of the sensing bit assembly to said element for corresponding movement of said element relatively to the main body, and means for translating relative movement of said element to a signal for indicating the advance of said sensing bit assembly into material of different hardness from said selected material.

12. A mining machine cutting and breaking arm for removing selected material from a mine face, said cutting and breaking arm comprising a main body, a sensing bit exteriorly mounted on the main body for movement relatively to the main body when the sensing bit is advanced into material of different hardness from said selected material to sense said different hardness material of the mine \face, an element supported in said main body for movement relatively to the main body, said element extending beyond the main body to cooperate with the sensing bit to oppose movement thereof and for transmitting relative movement of the sensing bit to said element :for corresponding movement of said element relatively to the main body, and means for translating relative movement of said element to a signal for indicating the advance of said sensing bit into material of different hardness from said selected material.

References Cited in the file of this patent UNITED STATES PATENTS 2,752,591 Felbeck et al. June 26, 1956 

12. A MINING MACHINE CUTTING AND BREAKING ARM FOR REMOVING SELECTED MATERIAL FROM A MINE FACE, SAID CUTTING AND BREAKING ARM COMPRISING A MAIN BODY, A SENSING BIT EXTERIORLY MOUNTED ON THE MAIN BODY FOR MOVEMENT RELATIVELY TO THE MAIN BODY WHEN THE SENSING BIT IS ADVANCED INTO MATERIAL OF DIFFERENT HARDNESS FROM SAID SELECTED MATERIAL TO SENSE SAID DIFFERENT HARDNESS MATERIAL OF THE MINE FACE, AN ELEMENT SUPPORTED IN SAID MAIN BODY FOR MOVEMENT RELATIVELY TO THE MAIN BODY, SAID ELEMENT EXTENDING BEYOND THE MAIN BODY TO COOPERATE WITH THE SENSING BIT TO OPPOSE MOVEMENT THEREOF AND FOR TRANSMITTING RELATIVE MOVEMENT OF THE SENSING BIT TO SAID ELEMENT FOR CORRESPONDING MOVEMENT OF SAID ELEMENT RELATIVELY TO THE MAIN BODY, AND MEANS FOR TRANSLATING RELATIVE MOVEMENT OF SAID ELEMENT TO A SIGNAL 